Triangular waveform generator circuits are used in a variety of applications. For example, triangular waveform generator circuits are used in microelectronics, telecommunications, and signal processing applications. Triangular waveform generator circuits are also used to charge and maintain rechargeable batteries. Existing charging circuits typically apply a charging signal to a battery to replenish its charge. Examples of such prior art circuits may be found in the U.S. Pat. Nos. 4,871,959, 5,084,664, 5,063,341, 5,276,393, and 5,633,575 and U.S. Reissue Pat. No. RE35,643, the disclosures of which are hereby incorporated by reference. In order to increase operating efficiency of a charging circuit, it is desirable to remove sulphate buildup in battery plates. Existing charging circuits do not efficiently remove sulphates from the battery plates.